Grease composition

ABSTRACT

Lubricating fluids thickened to greases with aromatic polyamides derived from 4,4&#39;&#39;-diaminodiphenyl sulfone and phthaloyl acid chlorides.

United States Patent Nipe 1451 Dec. 31, 1974 GREASE COMPOSITION 3,622,514 11/1971 Dickert et al 252/475 3,641,004 2/1972 252/475 [75] Inventor: Munster 3,674,691 7/1972 Karll et al. 252/475 73 Assigneez Standard Oil Company, Chicago, 1 3,749,695 7/1973 Vries 252/475 [22] Filed: 1974 Primary Examiner-Daniel E. Wyman [21] A N 441,015 Assistant Examiner-I. Vaughn Attorney, Agent, or FirmEdwin C. Lehner; Arthur G. G'lk W'll T. M Cl 52 US. Cl 252/475, 252/49.6, 252/54 es am [51] Int. Cl. C10m 5/22, CiOm 7/36 58 Field of Search 252/475, 54, 49.6 57] ABSTRACT Lubricating fluids thickened to greases with aromatic [56] References Cited polyamides derived from 4,4'-diaminodiphenyl sulfone and phthaloyl acid chlorides.

4 Claims, No Drawings GREASE COMPOSITION The invention herein described was made in the course of or under a contract with the Department of the Air Force.

FIELD OF THE INVENTION 1. Background of the Invention This invention relates to lubricating grease compositions in which the thickening agent is an aromatic polyphthalamide.

2. Description of the Prior Art In my US. Pat. No. 3,773,666, granted Nov. 20, 1973, I disclosed the use of certain polyphthalamides as thickening agents for the formation of lubricating greases.

SUMMARY OF THE INVENTION The lubricant greases of this invention comprise a lubricating fluid and a thickening amount of from about 3 to about 50, usually 5 to 25, and most preferably 5 to 10, weight percent of a finely-divided solid, thermally stable, essentially linear aromatic polyamide, insoluble in said fluid, selected from the group consisting of (a) the polyamide derived from substantially equimolar proportions of 4,4-diaminodiphenyl sulfone (hereinafter sometimes referred to for convenience as APS) and terephthaloyl dichloride and (b) the polyamide derived from substantially equimolar proportions of 4,4-diaminodiphenyl sulfone and a phthaloyl acid chloride mixture consisting of about 75 mol percent terephthaloyl dichloride and about mol percent isophthaloyl dichloride.

The lubricating fluid component of the greases of this invention can be any normally liquid lubricating oil or fluid of natural or synthetic origin that is normally used in lubricant grease compositions. Illustrative of such oils are the conventional mineral lubricating oils and synthetic lubricating fluids or oils, such as silicone oils, fluorosilicone oils, polyether fluids, polyester fluids, polyfluoro fluids, etc., having viscosities within lubricating oil viscosity range.

The lubricant grease compositions of the present invention can contain, if desired, lubricant additives well known to the art without departing from the scope of the invention. For example, such greases can contain corrosion and/or rust inhibitors, E.P. agents, antioxidants, metal deactivators, stabilizers, anti-wear agents, and the like. The use of such additives and the amounts thereof depend upon the severity of the conditions to which the grease may be subjected.

The polyamide thickeners of this invention are finelydivided thermally stable solid materials which are inert and insoluble in the lubricating fluid. The term thermally stable means that the thickener does notmelt or soften at grease operating temperatures.

The grease compositions are prepared by simply dispersing the solid polyamide thickener, in finely divided particulate forms, such as a powder, in the fluid and then milling the dispersion mixture to the desired grease consistency. Any method of mixing that imparts shearing action may be used. Preferably, the conventional grease roll mill is used to form a grease having a stable consistency or penetration. The particle size of the thickener is not critical, but the particles should be as small as possible, since it is well known that the stability of the grease is dependent upon the particle size of the solid thickener. Inasmuch as the polyamide thickener is inert and insoluble in the lubricating fluid, it is to be understood that a plurality of passes through a roll mill and adjustment of fluid content are required to obtain homogenity of the solid thickener/fluid system and effect a stable consistency in the grease.

The CRC L-35 bearing performance test was used to determine the performance of the exemplary grease formulations of this invention as bearing lubricants at elevated operating temperatures. The size 204 test bearings, with a 50 pound radial load and a 25 pound axial load on the bearing, were run continuously in high speed test spindles at 100,000 rpm, in air and at atmospheric pressure, at the test temperatures until failure.

The polyamides used in the present invention are high molecular weight, generally 10,000 or more, condensation products of substantially equimolar proportions of the described diamine and dibasic acid chlorides prepared by well known techniques for such products useful in fiber, film, coating and plastic industries. The present invention is limited to the use of the described polyamides as grease-forming thickeners in lubricating oils and fluids. Accordingly, such polyamides per se and their preparation do not constitute any part of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The quarter-cone penetration of the exemplary greases of this invention was determined by ASTM Method D-l403.

EXAMPLE I A solution containing 24.8 g. (0.1 mol) ofAPS in 195 g. of N,N-dimethylacetamide (DMAC) was prepared in a three liter round bottom flask equipped with nitrogen purge, stirrer, addition funnel, and thermometer. To this solution was added 20.3 g. (0.1 mol) of terephthaloyl dichloride, with stirring, over a 30 minute period at a temperature of 22-24 C. The solution temperature was raised to 50 C. and stirred for 20 minutes at which time a slurry formed. After addition of g. of DMAC, the slurry was added to distilled water in a Waring Blendor and the polyamide precipitated. After precipitation the polymer was washed with distilled water to an aqueous pH of 4.5 to remove hydrogen chloride and then filtered. The wet finely divided polymer particles were then dried overnight in a vacuum oven at 50 C. and identified herein as polyamide A.

Silicone polymer lubricating fluid, Dow-Corning F6- 7039, was thickened with 5.7 g. of polyamide A on a three-roll grease mill. The grease obtained had a quarter-cone penetration of 321 and had a hearing test life of 34 hours at 600 F. A portion of this grease after heat treatment of 550 F. for 1 hour and remilled had a penetration of 317 and ran for 54 hours at 600 F. in the hearing test. A grease comprising Krytox I43 AD, a perfluorinated polyether lubricating fluid derived from hexafluoropropylene oxide, and 5.7% of polyamide A, had a penetration of 296 and ran for 240 hours at 550 F. in the bearing test. A Krytox-based grease containing 6.0 wt. polyamide A thickener and 3.0 wt. of M-4" (a duPont anti-corrosion additive) had a penetration of 296 and a bearing test life of 385 hours at 550 F.

EXAMPLE II Polyamide B, a mixed polyamide derived from APS and phthaloyl dichloride mixture of 75 mol terephthaloyl dichloride and 25 mol isophthaloyl dichloride, was prepared as follows: To a solution containing 24.8 g. (0.1 mol) APS in 195 g. DMAC was added a melted mixture (0.1 mol) of 15.2 g. terephthaloyl dichloride and 5.2 g. of isophthaloyl dichloride over a minute period at a solution temperature of 29 C. The solution, with stirring was then heated to 50 C. and held for 2 hours. Thereafter the polymer was precipitated in distilled water in a Waring Blendor, washed and dried as in Example 1.

A grease comprising F6-7039 silicone lubricating fluid and 8.5% polyamide B had a penetration of 313 and a bearing test life of 47 hours at 600 F.

A series of greases using Krytox 143 AD as the lubricating fluid thickened with polyamide B were prepared. Grease 1 containing 5.6% thickener and 2.8 wt. M-4 had a penetration of 296 and a bearing test life at 550 F. of 445 hours and 1,678 hours in separate tests. Grease 11 containing 5.4% thickener had a penetration of 311 and a bearing test life of 228 hours at 550 F. Grease 111 containing 5.8% thickener had a penetration of 308 and a bearing test life of 260 hours at 550 F. Grease IV containing 5.5% thickener, 1.0% M-4 and 3.0% ammeline (supplementary thickener) had a penetration of 300 and a bearing test life of 445 hours at 550 F. Grease V containing 5.5% thickener, 1.8% M-4" and 3.0% ammeline had a penetration of 317 and a bearing test life of 250 hours at 550 F. Grease VI containing 5.8% thickener had a penetration of 308 and ran for 256 hours in the bearing test at 550 F. at which time the test was terminated due to corrosion debris but the grease was still soft in the bearing.

EXAMPLE Ill Polyamide C, a mixed polyamide as described in Example 2, was prepared as follows: To a solution of 74.4 g. (0.3 mol) of APS in 585 g. DMAC was added with stirring a mixture (0.3 mol) of 45.6 g. terephthaloyl dichloride and 15.6 g. isophthaloyl dichloride crystals over 45 minutes at a solution temperature of 25-35 C. and then stirred without additional heat for 2.5 hours at which time a haze developed in the solution. The polyamide formed was then precipitated in distilled water, washed and dried as described in Example 1.

A grease consisting of Krytox 143 AD" lubricating fluid, 5.7 wt. polyamide C, and 3.0 wt. M-4" corrosion inhibitor and having a penetration of 296 was prepared by milling on the three-roll grease mill. This grease ran for 189, 324 and 321 hours in three separate bearing tests at 550 F.

While the phthalamide thickeners disclosed in my aforesaid US. Pat. No. 3,773,666 are efficient thickening agents for lubricating fluids, it will be apparent to one skilled in the art that the polyamides described herein are more efficient thickening agents for the examples illustrate that much less thickener is required to form greases of similar consistency.

I claim:

1. The grease composition comprising a lubricating fluid and a thickening amount of from 3 to about 50 weight percent of a finely-divided solid, thermally stable, essentially linear aromatic polyamide, insoluble in said fluid, selected from the group consisting of (a) the polyamide derived from substantially equimolar proportions of 4,4'-diaminodiphenyl sulfone and terephthaloyl dichloride and (b) the polyamide derived from substantially equimolar proportions of 4,4- diaminodiphenyl sulfone and a phthaloyl acid chloride mixture consisting of about 75 mol percent terephthaloyl dichloride and about 25 mol percent isophthaloyl dichloride.

2. The composition of claim 1 wherein said lubricating fluid is a perfluorinated polyether fluid.

3. The composition of claim 1 wherein said lubricating fluid is a silicone polymer lubricating fluid.

4. The composition of claim 1 wherein the amount of said polyamide is from about 5 to about 25 weight percent.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,357,797 DATED December 31, 1974 INVENTOR(S) I RICHARD N. NIPE It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: I

C01. 2, line 12, for "100,000" read 10,000

Signed and sealed this 6th day of May 1975.

(SEAL) Attest:

C. MARSHALL DANN RUTH C. MASON I Commissioner of Patents Attesting Officer and Trademarks 

2. The composition of claim 1 wherein said lubricating fluid is a perfluorinated polyether fluid.
 3. The composition of claim 1 wherein said lubricating fluid is a silicone polymer lubricatinG fluid.
 4. The composition of claim 1 wherein the amount of said polyamide is from about 5 to about 25 weight percent. 